Thank you for your response.
Considering we're arriving at the airport the day before our cruise and have booked a hotel adjacent to the Roma Termini station, I think we've got a great setup for a convenient journey to the port. Since we'll already be taking the train from the airport to Termini, it's likely just as easy to continue on to the port by train the next day.
That being said, I do appreciate the idea of taking a dedicated transport to the port, such as a private car or taxi, for a more relaxed and hassle-free experience. It's definitely worth pricing out both options to see which one makes more sense for us. Either way, I'm looking forward to a comfortable and stress-free journey to the port with my wonderful wife!
Alan